Health officials in New York state say they have a new focus in their investigation into the cases of severe respiratory illnesses that have been linked to vaping. There are more than 200 reported cases in the U.S. of people falling seriously ill and then ending up hospitalized after they have used e-cigarettes. Here's NPR's Allison Aubrey.

ALLISON AUBREY, BYLINE: Among the people who've gotten sick, some have handed over the vaping cartridges they used, and investigators in New York have analyzed the samples in a lab. What they've found are very high levels of vitamin E in the products that also contain THC or cannabis. Health Commissioner Howard Zucker says these products are not coming from approved medical marijuana dispensaries in New York, but appear to be black market cartridges purchased off the street.

HOWARD ZUCKER: This is a situation of people buying products that have been laced with markedly elevated amounts of vitamin E.

AUBREY: Vitamin E is common as a dietary supplement, it's also found in lotions. But when it's vaped, especially in high concentrations, Zucker says it could be harmful.

ZUCKER: Vitamin E inhaled deep in the lung can cause problems.

AUBREY: The people who've gotten sick have shown up in emergency rooms with shortness of breath and chest pain. And Zucker says imaging of their lungs points to inflammation.

ZUCKER: This is an inflammatory process in the lung. The body is trying to fight off a foreign substance deep in the lung.

AUBREY: Vitamin E may be one explanation for the cluster of illnesses. Cases have been reported in at least 25 states, and two deaths are linked to the vaping-induced sicknesses, one in Illinois and one in Oregon. Zucker says the investigation is ongoing.

ZUCKER: We have not ruled out any other substances.

AUBREY: Officials at the FDA say no one substance, including vitamin E, has been identified in all of the samples tested around the country. The agency says more information is needed to understand whether any specific product or substance is linked to all of the illnesses.